Transfer sheets for duplicating



July 29, 1969 D. A. NEWMAN 3,458,339

TRANSFER SHEETS FOR DUPLICATING Filed Oct. ,24, 1967 2O MASTER SHEET W |2 i561/ j [IMI/M Qwewepaa Lm/Ele xo- FILM FOUND/ATT IIM A m1 "0 'MBGES 25- co PY 5m-EET INVENTOR .Daag/ZS 9. MSW/7700 #Tram/E73* United States Patent O 3,458,339 TRANSFER SHEETS FOR DUPLICATING Douglas A. Newman, Glen Cove, N.Y., assignor to Columbia Ribbon and Carbon Manufacturing Co.,

Inc., Glen Cove, N.Y., a corporation of New York Continuation-in-part of application Ser. No. 496,526,

Oct. 15, 1965. This application Oct. 24, 1967, Ser.

Int. Cl. B41c 1/06; D21h J/28 U.S. Cl. 117-36.4 5 Claims ABSTRACT OF THE DISCLOSURE Transfer sheets having a flexible foundation carrying a normally non-pressure-transferable porous layer comprising a resinous binder material having dispersed therein an incompatible liquid ink, characterized by the foundation having a smooth plastic release surface and the porous layer having thereon a frangible supercoating whereby the porous layer is rendered transferable under the effects of impact pressure to form squeeze-out type duplicating images on a master sheet.

This application is a continuation-in-part of parent application Ser. No. 496,526, filed Oct. 15, 1965, now U.S. Patent No. 3,359,900. A

The transfer sheets of the present invention are adapted for use in the duplicating system of the parent application for the production of a limited number of copies, up to about 25 or so, of original subject matter applied to a master sheet from such a transfer sheet under the effects of impact pressure. Such a system is not intended to compete with multicopy system such as hectography where several hundred copies can be produced from imaged master sheets.

The conventional hectograph process enjoys widespread commercial success but is too expensive and inconvenient for use in certain applications where only a small number of duplicate copies are required and only at spaced intervals. The spirit duplicating machine is rather expensive and the dye solvents used therein are volatile. If such a machine is used only occasionally and only for the production of a few copies each time, then the cost per copy is high. Also the volatile dye solvent evaporates over a period of time so that the supply must be checked and refilled frequently.

Dry copy systems have been proposed for the production of a limited number of copies but these also have ydisadvantages which restrict their use to certain limited fields of application where the quality of the copy produced is not critical. According to these systems, a conventional hectograph master sheet is typed and then pressed against copy sheets to transfer dyestuff to each copy sheet. In all of these processes the images typed onto the master sheet are conventional hectograph images containing a major amount of undissolved hectograph dyestuff in a frangible binder material.

According to one of these processes are copy sheets pressed against the master images are ordinary paper sheets and the images formed on each sheet are merely portions of the master images which are pressurearansferred to the copy sheets and contain undissolved dyestuff and frangible binder material. Such images are soft and easily spreadable or smearable upon contact with the hands and are exceptionally dirty to the touch due to the presence of the undissolved dyestuff which has a high staining power.

According to other of these processes, the copy sheets carry a solid coating which contains a material having a dissolving power for the hectograph dyestufi. Unless the dye solvent requires heat activation, the formed copies are of very poor quality due to a broadening of the duplicate images as solvation continues with time. On the other hand, heat-activatable dye solvents require the use of a heat source in addition to the higher cost of solvent coated copy sheets as compared to conventional uncoated hectograph copy papers.

With all of these considerations in mind, it is the main object of the present invention to provide transfer sheets which permit the user to make a limited number of high quality duplicate copies from a typed master sheet onto conventional untreated copy papers and in the absence of volatile dye solvents and expensive duplicating apparatus.

It is another object of this invention to provide duplieating transfer sheets which do not require the use of undissolved hectograph dyestuff and which therefore avoid the disadvantages thereof.

These and other objects and advantages of the present invention will be clear to those skilled in the art in the light of the following description including the drawings, in which:

FIGURES 1 and 2 are diagrammatic cross-sections, to enlarged scales, of transfer sheets and master sheets according to various embodiments of the present invention. In each case the sheets are shown in spaced relationship, for purposes of illustration, and illustrate the images formed on the face of the master sheet as a result of applying imaging pressure against the back of the master sheet while it is in intimate surface contact with the transfer layer of the transfer sheet.

FIG. 3 is a diagrammatic cross-section, to an enlarged scale, of the master sheet of FIG. 1 together with a copy sheet imaged therewith. The sheets are shown in spaced relationship, for purposes of illustration, and the duplicate images on the copy sheet were formed by pressing the master sheet against the copy sheet surface while the master images were in intimate surface contact therewith.

According to the present nvention, pressure-sensitive transfer sheets are provided which carry a layer capable of being mass transferred or stencilled in image form to a master sheet under the effects of localized imaging or impact pressure and containing a supply of pressure-extrudable ink capable of being metered from -the master sheet images to a succession of copy sheets under the effects of overall pressure of lower magnitude than said impact pressure.

The present invention is based upon the requirement that the imaging layer of the Itransfer sheet must have the apparently contradictory properties of Ibeing mass transferable from the transfer sheet under the effects of impact pressure and being non-transferable as a mass from' the master sheet under the effects of overall pressure of lower magnitude than said impact pressure. Once the images are formed on the master sheet they must be capable of exuding liquid non-drying ink to a succession of copy sheets under the effects of overall pressure rather than transferring in mass to the first copy sheet against which it is pressed. While these properties may appear to be contradictory, they are not, Ebecause of the fact that the pressures involved are quite different, but more importantly because the affinity of the imaging layer for its foundation can be reduced while increasing the ainity of the imaging layer for the master sheet. Thus while the imaging layer itself may normally be non-frangible, other forces may be interposed to overcome this property.

According to the present invention, as illustrated fby FIGS. 1 and 2, it is possible to use imaging layers which have reduced frangibility and increased squeeze-out action by supplementing the poor frangibility of the imaging layer by means of a supercoating and a release surface.

According to FIG. 1, the transfer sheet has a smooth plastic film foundation carrying the imaging layer 12 and a frangible supercoating 13. The imaging layer has poor frangibility per se, so as to be normally non-transferable per se to the master sheet, but the smooth surface of the foundtion readily releases the imaging layer while at the same time the supercoating anchors it to the master sheet totenable the transfer and to prevent otset during the duplicating step. The supercoating 13 is a coating having good frangibility and having good adhesion properties for both the imaging layer and the master sheet. Under the effects of imaging pressure, the supercoating transfers sharply and cleanly to the master sheet shown as images 13a and carries with it corresponding areas of the imaging layer shown as images 12a. The supercoating bonds to the surface of the master sheet and forms a strong anchor for the transferred portions of the imaging layer so that images 12a remain bonded to the master sheet and function to exude non-drying ink under the effects of the duplicating pressure. At the same time, the smooth surface of the film foundation readily releases the imaging layer since it is not integrated therewith and is only weakly bonded thereto. A paper foundation will not function in this manner since it is porous and thus the imaging layer is able to penetrate the paper surface and form a strong bond therewith in the course of applica-tion. Of course the plastic lm foundation must be one which is insoluble in the volatile solvent used to apply the imaging layer.

In another embodiment, as shown by FIG. 2 of the drawing, the supercoated imaging layer 12 may be provided with a release layer 14 between it and a paper foundation sheet 30. This embodiment is of importance in cases where it is desired to use a paper foundation. Normally the imaging layer tends to form such a strong bond to a porous paper foundation that it resists transfer under the effects of imaging pressure. In such cases the lack of frangibility is overcome by reducing the degree of bond permitted between the imaging layer and the paper foundation. This is accomplished by the embodiment shown in FIG. 2 in which the paper foundation is first coated with a smooth non-transferable continuous release layer based mainly or entirely upon a plastic binder material such as a vinyl resin which is insoluble in the volatile solvent used -to apply the imaging layer.

In all cases the imaging layers of the present invention comprise a microporous structure or network of synthetic thermoplastic binder material having in the pores thereof an exudable liquid ink comprising a vehicle and coloring matter. The vehicle contains at least 30% by weight of a liquid oily material and is incompatible with the binder, by which is meant that it is a non-solvent for the binder and immiscible therewith. The coloring matter is preferably a dyestuff dissolved in the ink vehicle, but pigments are also suitable.

The following examples are given as illustrations of compositions and methods suitable for the production of transfer sheets according to the embodiments of the present invention and should not be considered limitative.

Example 1 This example illustrates the preparation of a transfer sheet of the type illustrated by FIG. 1 of the drawing in which the imaging layer is present on a smooth plastic film foundation.

Ingredients: Parts by weight Vinyl chloride-vinyl acetate copolymer (vinylite VYHH) 13.7

Oleic acid 23.5

Methyl violet 3.8

Victoria blue 1.2

Clay 12.5 Methyl ethyl ketone 45.3

CII

The above ingredients were mixed to a coatable consistency and applied to a thin polyethylene terephthalate polyester film in conventional manner. After drying by evaporating the volatile solvent, the imaging layer has applied thereover a thin supercoating which has good frangibility. The following composition is illustrative:

Ingredients: Parts by Weight Carnauba wax 58 Polybutene resin (Indopol H-300) 8 Beeswax 8 Mineral oil 26 The supercoating is applied to the surface of the imaging layer as a hot melt and cooled. Under the effects of imaging pressure, the supercoating carries corresponding portions of the imaging layer to the master sheet as shown by FIG. 1.

Example 2 This example illustrates the use of a paper foundation provided with a smooth non-pressure-transferable plastic release layer as a support for the normally non-transferable imaging layer and frangible supercoating of Example 1.

A paper sheet such as 51/2 lb. kraft paper is coated on one surface with a 10% solution of polyvinyl butyral (Vinylite XYSG) in ethyl alcohol in an amount equal to about three poundsper ream 25" x 3S X 500 sheets and the solvent is evaporated to form a smooth non-pressuretransfer-able continuous plastic release layer 14 on the paper surface 30 as shown in FIG, 2. Thereafter the imaging composition of Example l is applied over the release layer and the supercoating of Example l is applied over the imaging layer.

Under the effects of impact -pressure the release layer readily releases the imaging layer and the supercoating bonds firmly to the surface of the master sheet to effect the transfer as shown in FIG. 2.

The master sheets 20 imaged according to the present invention, such as those shown in FIGS. 1 to 3, are used to produce duplicate copies in any number of conventional pressure devices which provide an overall pressure of lower magnitude than impact pressure. A conventional hectograph duplicating machine may be used without the usual spirit solvent provided that the pressure between the master sheet, mounted on the rotating drum, and the copy sheets is increased so that exudation of the ink to the copy sheets results. Similarly a Thermo-Fax or the like machine may be used provided that it has pressure -rollers to compress the master sheet and copy sheet to the extent necessary to cause ink exudation. In such machines the infrared radiation source may be retained since heating of the master images tends to render the ink more fiuid and thus more easily exudable under the applied pressure. Other conventional pressure devices such as a fiat press which applies overall pressure or a knife edge device which applies line pressure may be used.

In operation, `as illustrated by FIG. 3, the duplicating images function by squeezing the incompatible ink from the porous resin network of the portions 12a of the imaging layer bonded to the master sheet by means of the rportions 13a of the supercoating. The liquid ink is exuded from the resinous network, with which it is incompatible, and stains the surface of the copy sheet 2S, against which it is pressed, to form duplicate images 11b which correspond in reverse to the subject matter of the master images. The master images are generally mirror-reversereading images and the copy sheet images are directreading images.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. A transfer sheet comprising:

(a) a flexible foundation having a smooth plastic release surface,

5 6 (b) a normally non-frangible porous imaging layer of flexible foundation is paper having thereon a continuous composition comprising a network of resinous binder smooth 'PlaSC Coating forming The release Surface material having dispersed therein an ink which is 4. A transfer sheet according to claim 1 in which the liquid at ordinary room temperatures and comprises lmagmg layer cOmPflSeS a VlIlyl reSlIl bllldef mater 1211 and the ink comprises a dyestuff dissolved in said oil.

5. A t-ransfer sheet according to claim 1 in which the supercoating `comprises a resinous material.

coloring matter and an oil which is incompatible 5 with the said binder material, and

(c) a frangible layer of supercoating composition over 'said imaging layer and which has good aiiinity for References Cited both sald imaglng layer and for the surface of a master sheet, whereby under the eiTects of impact 10 UNITED STATES PATENTS imaging pressure the supercoating is capable of 2,508,725 5/ 1950 Newman 117-3674 transferring in image form to `a master sheet and of 2,943,952 7/ 1960 Clark 117-364 carrying with it corresponding portions of the imag- 2,934,582 5/1961 Newman et 3L 117*-35-4 ing layer released by the surface of the foundation 15 3,252,413 5/1966 Sharkey 117-36-1 sheet and of bonding the portions of the imaging Irrftk layer to the master sheet so that such portions can 3,359,900 12/1967 Newman u 11,/ 364 exude the liquid ink to a succession of copy sheets pressed thereagainst at an overall pressure of lower MURRAY KATZ Primary Examiner magnitude than said impact imaging pressure. 20 2. A transfer sheet according to yclaim 1 in which the U.S. Cl. X.R. tiexible foundation is a smooth plastic film.

3. A transfer sheet according to claim 1 in which the lOl-468 117 76 155 

